﻿/*
 * VerticalDatumType
 * 
 * initial implementation : 20.11.2008
 *
 * Copyright (c) Adam Sida, asida@centrum.cz.
 * All rights reserved.
 * 
 * for license see Petra.Gis.License.txt
 */
using System;


namespace Petra.Gis.ReferenceSystemServices
{
  public enum VerticalDatumType : int
  {
    /// <summary>
    /// Unspecified vertical datum type.
    /// </summary>
    Unspecified = 2000,

    /// <summary>
    /// A vertical datum for orthometric heights that are measured along the plumb line.
    /// </summary>
    Orthometric = 2001,

    /// <summary>
    /// A vertical datum for ellipsoidal heights that are measured along the normal to
    /// the ellipsoid used in the definition of horizontal datum.
    /// </summary>
    Ellipsoidal = 2002,

    /// <summary>
    /// The vertical datum of altitudes or heights in the atmosphere. These are
    /// approximations of orthometric heights obtained with the help of a barometer or
    /// a barometric altimeter. These values are usually expressed in one of the
    /// following units: meters, feet, millibars (used to measure pressure levels), or
    /// theta value (units used to measure geopotential height).
    /// </summary>
    AltitudeBarometric = 2003,

    /// <summary>
    /// A normal height system.
    /// </summary>
    Normal = 2004,

    /// <summary>
    /// A vertical datum of geoid model derived heights, also called GPS-derived heights.
    /// These heights are approximations of orthometric heights (H), constructed from the
    /// ellipsoidal heights (h) by the use of the given geoid undulation model (N) 
    /// through the equation: H=h-N.
    /// </summary>
    GeoidModelDerived = 2005,

    /// <summary>
    /// This attribute is used to support the set of datums generated for hydrographic
    /// engineering projects where depth measurements below sea level are needed. It is
    /// often called a hydrographic or a marine datum. Depths are measured in the 
    /// direction perpendicular (approximately) to the actual equipotential surfaces of
    /// the earth's gravity field, using such procedures as echo-sounding.
    /// </summary>
    Depth = 2006

  }
}
